Endoprosthesis for the hipjoint

ABSTRACT

An endoprosthesis for the hip joint includes a head portion, or artificial femoral head, and a substantially elbow-shaped member of polyethylene resiliently supporting said head portion. The elbow-shaped member includes a relatively short upper portion and a relatively long lower portion and defines at the junction of these two portions on one side a concave bent and on the other side a convex bent. Each of both portions is provided with an internal channel. One of these channels is substantially coaxial with the upper portion of said elbow-shaped member and has an entrance or opening situated at the convex bent of said elbowshaped member. The other of these channels is substantially coaxial with said lower portion of said elbow-shaped member and has an entrance or opening situated at the upper portion of said elbow-shaped member. The aforementioned channels intersect at an obtuse angle and each of the aforementioned channels receives one of a pair of pins or studs. The upper head portion or artificial femoral head defines a slanting channel into which said upper portion of said elbow-shaped member of polyethylene projects.

United States Patent 1191 Timmermans 1 1 ENDOPROSTHESIS FOR THE HIPJOINT [76] lnventor: Franz Donatus Timmermans,

Brunswiker Strasse 1 la, 23 Kiel, Germany [221 Filed: Aug. 20, 1973 [21] Appl. No.: 390,138

Related U.S. Application Data [63] Continuation of Ser. No. 124,431, Aug. 23, 1971.

abandoned.

[52] U.S. Cl. ..3/1.913; 128/92 CA [51] Int. Cl. A6lf 1/24 [58] Field of Search ..3/1,1.913,l.912,1.91; 128/92 CA, 92 C, 92 R [56] References Cited UNITED STATES PATENTS 2,679,245 5/1954 Timmerrnans 128/92 CA 2,719,522 10/1955 Hudack 128/92 CA 2,781,758 2/1957 Chevalier 128/92 CA 3,064,645 11/1962 Ficat et a1. 128/92 CA 3,466,670 9/1969 Christiansen 3/1 FOREIGN PATENTS OR APPLICATIONS 1,122,634 5/1956 France 128/92 C 1,107,877 8/1955 France 128/92 C Primary Examin erRonald L. Frinks Attorney, Agent, or Firm-Erwin Salzer [57] ABSTRACT An endopros'thesis for the hip joint includes a head portion, or artificial femoral head, and a substantially elbow-shaped member of polyethylene resiliently supporting said head portion. The elbow-shaped member includes a relatively short upper portion and a relatively long lower portion and defines at the junction of these two portions on one side a concave bent and on the other side a convex bent. Each of both portions is provided with an internal channel. One of these channels is substantially coaxial with the upper portion of said elbow-shaped member and has an entrance or opening situated at the convex bent of said elbowshaped member. The other of these channels is substantially coaxial with said lower portion of said elbow-shaped member and has an entrance or opening situated at the upper portion of said elbow-shaped member. The aforementioned channels intersect at an obtuse angle and each of the aforementioned channels receives one of a pair of pins or studs. The upper head portion or artificial femoral head defines a slanting channel into which said upper portion of said elbowshaped member of polyethylene projects.

2 Claims, 3 Drawing Figures l ENDOPROSTHESIS FOR THE HIPJOINT This application is a continuation of application Ser. No. 124,431, filed Aug. 23, 1971 now abandon'ed.

BACKGROUND OF THE INVENTION This invention relates to a femoral endoprosthesis. This endoprosthesis calls for but a relatively simple resection of the natural femoral head which it replaces, allows a ready adaptation of it by the surgeon to the particular anatomy of his patient, and 'has a great di- SUMMARY or THE INVENTION An endoprosthesis embodying this invention includes a head portion or artificial femoral head which is at least in part of spherical shape and defines a first internal slanting channel. It further includes an elbowshaped member intended to perform the function of an intra-medullary nail. This substantially elbow-shaped member is of polyethylene and includes a relatively short upper portion projecting into said first slanting channel of said head portion and a relatively long lower portion enclosing an obtuse angle with said upper portion. Both portions of said elbow-shaped member define at the junction thereof at one side a convex bent and on the other side a concave bent. The aforementioned upper portion defines a second internal channel coaxial with said first internal channel of said head portion and having an entrance or opening situated at the region of said convex bent. The aforementioned lower portion of said substantially elbow-shaped member defines a third internal channel extending in a direction longitudinally thereof, intersecting with said second channel and having an entrance or opening situated at said upper portion of said elbow-shaped member. The prosthesis further includes a first pin and a second pin. The first pin has an end situated outside said elbowshaped member and projecting through said entrance or opening at said region of said convex bent of said elbow-shaped member into said upper portion thereof. The aforementioned second pin is arranged inside said third channel and inside said lower portion of said elbow-shaped member.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a femoral endoprosthesis embodying the present invention;

FIG. 2 shows in side elevation a detail of the structure of FIG. 1; and

FIG. 3 is substantially a longitudinal section of the structure of FIG. 1, showing some parts thereof in elevation rather than in section.

DESCRIPTION OF PREFERRED EMBODIMENT In the drawings reference character a has been applied to generally indicate an artificial femoral head of a hip joint prosthesis. The member a is at least in part spherical and defines a first internal slanting channel, i.e.. an internal channel slanting from the lower left to the upper right. The artificial femoral head a is supported by an intra-medullary nail g,h of polyethylene which is substantially elbow-shaped and includes the relatively short upper portion 12 and the relatively long lower portion g. Portion 11 projects into the aforementioned slanting channel in artificial femoral head a.

concave bent and at the other side the left side in FIGS. 1 and -3 a concave bent and at the other sidethe left sidein FIGS. '1 and 3 a convex bent. The

upperportion h of 'the intra-medullary nail gJz defines a second internal channel to which referencecharacter v has been applied. Channel v is arranged in coaxial relation to the aforementioned internal slanting channel in head a. Channel v has an entrance or-opening situa'tdat the region of the convex bent betweenportions g and h of member gJnThe lower portion. g of member g,h defines a third internal channel to which reference character I has been applied. Channel 1 extends in a direction longitudinally of the" portion g of intramedullary nail g,h, intersects said second channel v and has an entrance situated at theaforementioned upper portion 11 of elbow-shaped member gJi. Reference character a has been applied to indicate a-first pin having a pointed end situated outside member gJz and projecting through the region of the convex bent of member g,h into the upper portion 11 thereof. Reference character m has been applied to indicate a second pin arranged inside of channel I and inside the lower portion g of elbow-shaped member g,h. The head portion a is preferably of a plastic material and supports a metallic substantially spherical shell 12 shown in detail in FIG. 2. The body 0 of a resilient substance. e.g., rubber, is arranged at the end of said first channel of said head portion a adjacent said spherical shell b and is covered by the latter. The upper portion 12 of elbow-shaped member gJi is loosely inserted into said first channel in head portion a and abuts with one end surface thereof against said body 0 of said resilient substance. Reference character I has been applied to indicate the edge of metallic cap or shell b. The base 0 of head portion a has a rim :4 to which shell b is affixed. Reference character p has been applied to indicate cavities formed between shell and body 0 of resilient material, which may be a rubberlike substance.

FIG. 2 shows cap or shell b as being a deep drawn metal part being spherical at the top or apex and including a cylindrical lower portion q bounded by dotted lines r and s. Shell b may be affixed to base c by pressing. the cylindrical portion q thereof into rim u of head portion a.

The elbow-shaped member g,h of a thermoplastic material such as polyethylene is formed by machining a straight shaft, e.g., by means of a lathe, providing it with the above described channels and then imparting to it the desired elbow-shape upon heating thereof to about -l00 C. Channel 1/ is drilled to its full diameter to receive stud d only following bending of part g,h to its elbow-shape.

While performing the hip joint operation the surgeon may re-heat and re-shape part g,h in accordance with particular requirements. The pin or stud d is conical at its end remote from head a as indicated at f. Portion f of stud a is provided with a plastic cover e. The intramedullary nail gJz may be inserted in warm and soft ened condition upon resection of the natural femoral head. Rod m is inserted into part g,h after the latter has been inserted by the surgeon into place. Thereupon the surgeon drills a hole into the trachanter side of the resection and allows to propagate hip joint forces throughout the femur much as in the natural state. The dimensional stability of the present endoprosthesis is largely due to the presence of the two intersecting passages v,[ and that of the two pins in and (1. Part 0 of rubber or spongy material forms a particularly effective shock-absorber.

I claim as my invention: 1. A femoral head prosthesis including a. a head portion (a) being at least in part of spherical shape and defining a first internal slanting channel; b. a substantially elbow-shaped member (gJr) of polyethylene including a relatively short upper portion (11) projecting into said first slanting channel of said head portion (a) and a relatively long lower portion (g) enclosing an obtuse angle with said upper portion (11), said upper portion (h) and said lower portion (g) of said elbow-shaped member (gJr) defining at the junction thereof at one side a concave bent and at the other side a convex bent, said upper portion (11) defining a second internal channel (v) coaxial with said first internal channel of said head portion (a) having an entrance situated at the region of said convex bent, and said lower portion (g) defining a third internal channel (1) extending in a direction longitudinally thereof, intersecting said second channel (v) and having an entrance situated at said upper portion (11) of said elbow-shaped member (gJz);

c. a first pin (d) having an end situated outside said elbow-shaped member (g,h) and projecting through said entrance at said region of said convex bent of said elbow-shaped member (gJi) into said upper portion (11) thereof; and

d. a second pin (m) arranged inside said third channel (I) and inside said lower portion (g) of said elbow-shaped member (g,h).

2. A femoral head prosthesis as specified in claim 1 wherein said head portion (a) is of a plastic material and supports a metallic substantially spherical shell (b), wherein a body (0) of a resilient substance is arranged at the end of said first channel of said head portion adjacent said spherical shell, and wherein said upper portion (11) of said elbow-shaped member (g,h) is loosely inserted into said first channel of said head portion and ab'uts with one end surface thereof against said body of said resilient substance. 

1. A femoral head prosthesis including a. a head portion (a) being at least in part of spherical shape and defining a first internal slanting channel; b. a substantially elbow-shaped member (g,h) of polyethylene including a relatively short upper portion (h) projecting into said first slanting channel of said head portion (a) and a relatively long lower portion (g) enclosing an obtuse angle with said upper portion (h), said upper portion (h) and said lower portion (g) of said elbow-shaped member (g,h) defining at the junction thereof at one side a concave bent and at the other side a convex bent, said upper portion (h) defining a second internal channel (v) coaxial with said first internal channel of said head portion (a) having an entrance situated at the region of said convex bent, and said lower portion (g) defining a third internal channel (l) extending in a direction longitudinally thereof, intersecting said second channel (v) and having an entrance situated at said upper portion (h) of said elbow-shaped member (g,h); c. a first pin (d) having an end situated outside said elbowshaped member (g,h) and projecting through said entrance at said region of said convex bent of said elbow-shaped member (g, h) into said upper portion (h) thereof; and d. a second pin (m) arranged inside said third channel (l) and inside said lower portion (g) of said elbow-shaped member (g, h).
 2. A femoral head prosthesis as specified in claim 1 wherein said head portion (a) is of a plastic material and supports a metallic substantially spherical shell (b), wherein a body (o) of a resilient substance is arranged at the end of said first channel of said head portion adjacent said spherical shell, and wherein said upper portion (h) of said elbow-shaped member (g, h) is loosely inserted into said first channel of said head portion and abuts with one end surface thereof against said body of said resilient substance. 